Mr. Ferguson, whose official first name is Christopher, was the mathematically minded Ph.D.; Mr. Lederer, the strategic Kasparov of Texas Hold 'Em.
Earlier, a law enforcement official mistakenly transposed the brothers' first names.
The Venezuelan ombudsman, Tarek William Saab, a federal official charged with defending human rights, said on Twitter that he deplored the "vile murder" of the teen, who he named as Kluiverth Roa, though other officials spelled his first name differently.
FOR THE RECORD: Sheriff's Department: An article in the June 7 LATExtra section about the obstruction of justice trial of six Los Angeles Sheriff's Department officials misspelled the first name of one of the defendants, Maricela Long, as Maricella.
In the official White House schedule, her first name was misspelled, as "Teresa".
Also on Sunday a senior military officer, Gen Shi Luze, became the first named official to confirm the presence of the toxic chemical sodium cyanide at the site, saying that "several hundred tons" had been identified at two locations in the blast zone.
The man has previously been identified by government officials only by his first name, Dave.
Russian officials first refused to name the gas, then called it a version of fentanyl, a painkiller that can be lethal in high doses.
His promoter, Rock Newman, said at a news conference on Wednesday that Whitaker had filled out official paperwork to have his first name changed to Goofi.
In March 1999, German intelligence officials gave the CIA the first name and telephone number of Marwan al-Shehhi, and asked the Americans to track him.
German intelligence officials gave the C.I.A. the first name of the hijacker, Marwan al-Shehhi, and his phone number in early 1999 after monitoring conversations of a well-known Islamic extremist in Hamburg.
